Sheet handling apparatus



,J. w. MILLER SHEET HANDLING APPARATUS March 27, 1956 s sheets-sheet 1 Filed Jan. 18, 1955 NU 6 N Q M w w. A y r w n N I J QN B N\| IO \N J V m m 0 kw w 5 Q m N -n. nunnuhihfikuniiilllliriliuiiiununlnhhu1 3 R\ w 0 mm Q N W QM) R. .7 r T March 27, 1956 J. w. MILLER SHEET HANDLING APPARATUS Filed Jan. 18,'l955 INVENTOR. JOHN W M/MER f drmelvers H l ld 2 m 7 2 M 2 m/ s s a m 7 w s 3 3 5 3 I- I'H 5 O n ta I... Z/ 5 4 w 3 a llllll 0W x 9 w; n W 4 H 4 9 m 4 A .AU. ,.W 7 8 March 27, 19 6 J. w. MILLER SHEET HANDLING APPARATUS 5 Sheets-Sheet 3 Filed Jan. 18, 1955 w N M drraeMz-vs United States Patent SHEET HANDLING APPARATUS John W. Miller, Benton Harbor, Mich assignor to F. P.

Rosback Company, Benton Harbor, Mich, a corporation of Michigan Application January 18, 1955, Serial No. 482,493

Claims. (Cl. 271-62) This invention relates, as indicated, to apparatus for handling sheet material; more particularly, it is concerned with sheet feeding mechanism including a support and delivery device on which the sheets to be fed are arranged in the form of a stack and supplied to stripper means operative to remove and transfer the sheets individually from the top of the stack. I

My improved feed structure has been successfully employed in paper perforating apparatus, the feed mechanism functioning to deliver the sheets of paper to a conveyor which, in turn, transfers the same to the perforator proper. There are numerous other types of automatic and semi-automatic equipment, in which sheet material is similarly handled, for example printing presses, and, as will appear from the following detailed disclosure, the invention has general utility in such apparatus.

It is a primary object of the invention to provide an efficient and reliable feed mechanism of the type wherein sheets are removed from a supply stack of the same, including an automatically controlled support for such a stack which maintains the top thereof at a predetermined level as the height of the stack is progressively diminished by the sheet removal.

Another object is to provide a feed table or platform which is automatically gradually raised to bring stacked sheets supported thereon successively to a predetermined position with respect to a stationary transfer device operative to remove the sheets successively from the top of the stack.

It is also an object of the invention to provide a novel and improved control for regulating the lifting of such a stack support accurately in accordance with the elevation of a stack supported on the same, thereby to maintain the top of the stack at the predetermined level as sheets are continuously removed therefrom.

A further object is to provide a drive means for thus moving the stack support including a fluid connection, the effectiveness of which is under control of such elevation-responsive means.

It is an additional object to provide an improved sensing assembly adapted to indicate changes in the level of a supply stack of sheet material supported on a feed platform, the assembly being capable of adjustment such that it may be positioned above any selected portion of the platform.

Another object of the invention is to provide a motion transmitting device having an operative portion in the form of a readily controllable fluid connection.

It is also an object to provide sheet feeding mechanism comprising a fixed suction device and movable stack support means operative to bring successive sheets in the stack into operative relation to the suction device for removal by the latter.

A further object is to provide paper perforating apparatus characterized by novel means for feeding the sheets of paper to the perforating elements, the sheets being supplied to the apparatus in the form of a stack and the removal of the individual sheets therefrom being To the accomplishment of the foregoing and related ends, the invention, then, comprises the features hereinafter fully described and particularly pointed out in the claims, the following description and the annexed drawings setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but a few of the various ways in which the principle of the invention may be employed.

In said annexed drawings:

Fig. 1 is an elevational view of paper perforating apparatus which includes the improved feed structure of the present invention;

Fig. 2 is a top plan view of the sheet feeding mechanism of the apparatus;

Fig. 3 is an end elevational view of such mechanism, as viewed from the right in Fig. 1;

Fig. 4 is a fragmentary perspective view to an enlarged scale of the drive means for elevating the stack support of the feed mechanism;

Fig. 5 is an elevational view of the sensing assembly employed to control lifting of the stack support in response to the level of the top of the stack; and

Fig. 6 is a fragmentary view of this sensing assembly in another operative condition of the same.

Referring now to the drawings in detail, the complete nection of the various driven elements of the machine,

produces rotation of projecting shaft 13 and of shaft 14, the latter having a sheave 15 fixed thereon. The side of the machine indicated at 16 is the side at which the paper to be perforated is introduced, the sheets exiting on the delivery slide 17 at the opposite side.

In the construction illustrated, the conveyor means for transporting the sheets of paper to the perforator proper comprises a structural frame including side rail members 18. Journalled adjacent the respective ends of such rails so as to extend transversely thereof, are shafts 19 and 20, the latter shaft at the end of the conveyor assembly removed from the perforator, and engaged about the two shafts in spaced-apart relation are a number of endless tapes 21. A sheave 22 is fixed to shaft 20 at one end of the same and a drive belt 23 is engaged thereabout, about sheave 1S driven by the perforator and, for tensioning purposes, about a third idler sheave 24 connected by an angularly adjustable support 25 to the housing of the perforator.

Operation of the perforator therefore causes the conveyor tapes to move toward the perforator in their upper courses for the desired transfer of sheet deposited at the outer end portion of the same, shaft 2t) providing the driving power while shaft 19 rotates freely as an idler. The tapes may be arranged on a slight bias, that is, at an angle relative to the side rails 18, so that the sheets are carried against and move along one of the rails, thi; arrangement insuring uniform positioning of the sheets as delivered to the perforator.

The sheet feeding mechanism 12 is arranged adjacent the outer end of the conveyor structure 11 and is operative automatically to take sheets from the top of a supply stack and deposit them on the conveyor for transfer to the perforator in the manner noted. The mechanism includes a frame 26 within which a horizontal platform or support 27 is arranged for reception of a stackof the sheets indicated at 28. A number of vertically arranged guide bars 29 are secured to the frame member 30 at and spaced slightly from the inner edge of the platform and the stack is arranged thereagainst, as shown most clearly in Fig. 2, for alignment and guiding of the stack in its vertical movement. At each side, the platform is supported by a bracket 31 attached to a section of chain 32, the chains being driven in a manner to be described to raise the platform.

The device for removing the sheets from the vstack supported on the platform is in the form of a suction wheel 33 secured centrally to a shaft 34 which is supported in bearings 35 at the respective sides of the frame. Such shaft mounts the suction wheel at a fixed location at the top inner portion of the feeding mechanism and is driven by a connection with the conveyor drive shaft 20 so as to rotate the wheel in a clockwise direction as viewed in Fig. 1. This driving connection comprises a splitcone variable speed pulley 36 of commercially available type on conveyor shaft 20, a flat face pulley 37 on shaft 34, an idler pulley 33, and a V-belt 39 about the variable speed and idler pulleys. The belt is arranged so that its fiat surface engages the pulley 37 at the lower portion of the latter, thereby reversely to drive shaft 34, and by mounting the idler pulley on a support 40 pivotally secured to the frame, the latter may be shifted to vary the belt tension with a resultant'change in speed due to radial movement of the belt on the split-cone pulley 36, in wellknown manner. It is desirable thus to provide regulation of the suction wheel speed of rotation relative to the speed at which the conveyor tapes move, since this affords variable overlap of the sheets in stream feeding. Such adjustment is facilitated by an operating rod 41 secured at one end to the idler support 43 and having its other end threaded and passed through a bracket 42 on the frame. A thumb nut 43 is threaded on the outer end of the rod for convenient manual positioning of support 4! about its pivotalconnection.

Small substantially horizontal guides 44 are positioned just beneath the suction wheel to provide for sliding movement of the paper sheets toward the conveyor tapes 21 as a result of the lifting and carrying action of the wheel, the wheel operating thusly in conventional manner. A friction roll 45 i provided to grip the leading edge of each sheet as transferred cooperably with the tapes to insure that the transfer is accomplished without slippage.

Suction is applied to the wheel 33 by means of a shoe 46 overlying and held stationary at one end of the wheel. As customary, the adjacent end face of the Wheel is provided with a series of circumferentially spaced apertures 47, and a further communicating series of spaced apertures 43 is provided in the cylindrical wall thereof. The shoe applies suction at the lower peripheral portion of the rotating wheel effective to pick up and carry a sheet from the top of the stack a predetermined distance suliicient to transfer the same to the conveyor. A hose 49, which has been shown partially broken for convenience of illustration, extends from the lower region of the shoe 46 to a valve assembly 50 having a hose connection 51 leading to a suitable source of suction, for example, a motor-driven blower, not shown. This valve assembly is of a known type adapted to provide for either strike or stream feeding of the sheets by operation of a handle 52 controlling a barrel valve in the main suction line.

It will be clear that the top of the stack of sheets has a proper operating level relative to the suction wheel for the desired transfer action of the latter, and that, as sheets are successively removed, the stack should be elevated to maintain the top at such level. I provide, for this purpose, an automatically controlled drive and lift means operating on the platform support chains 32. The

chains are engaged respectively about drive sprockets 53 affixed to shafts 54, the shafts being supported for rotation in bearing assemblies 55. At the inner end of each shaft/54 is a worm gear 56, Fig. l, and a transverse shaft 57 is provided with worms 58 at the sides of the mechanism respectively in driving engagement with the worm gears 46. The gearing is such that rotation of the shaft in one direction, counter-clockwise in the illustrated structure, causes both chains to be actuated in a direction lifting the platform 27.

A latch bar 49 secured at one end of the suction shoe .6 has its other end slotted and engaged about shaft 57, thereby to hold the shoe stationary as the suction wheel shaft 34 passing therethrough rotates. At one side of the frame of the feeding mechanism, shaft 57 projects outwardly, has asprocket wheel 60 secured thereon, and terminates in a crank handle 61. A pawl 62 is pivotally mounted on a pin 63 held by spaced support blades 64 which are, in turn, rotatably mounted on shaft 57, the pawl being disposed for engagement with the sprocket wheel. Pawl 62 has a lever 65 extending tothe rear or oppositely from the sprocket-engaging end for rocking of the pawl about its pivotal connection with the support blades or cars 64.

Outwardly of such pivotal connection of the pawl, the upper end of a cylinder 66 is attached between the cars 64 and reciprocably received in the upper end portion of this cylinder is a first plunger 67 having an adjustable collar 68 thereon which limits movement of the plunger into the cylinder. The upper end 69 of plunger 67 is positioned beneath and in engagement with the lever 65 of the pawl, so that reciprocation of the plunger causes the pawl to oscillate between positions engaged with and disengaged from the sprocket wheel. in the normal depressed condition of plunger 67, the pawl i disengaged.

A second plunger 70 is mounted likewise for reciprocation in the lower end portion of the cylinder 66 and is provided with an adjustable collar 71 limiting upward movement of the same or penetration of this plunger into the cylinder. The collar 68 of the upper plunger and the collar 71 of the lower plunger are so positioned with respect to the respective lengths of the plungers, measured from the inner ends of the same, that the two are prevented from coming into direct contact when both are moved inwardly to their maximum extent.

There is, accordingly, defined within the cylinder and between the opposed ends of the two plungers a chamber 72 adapted to contain air. The dimensioning of the chamber is such that air scaled therewithin is effective to transmit the motion of one plunger to the other. Accordingly, when the chamber is exhausted of air, there will be no effective coupling between the plungers, but when filled and sealed with air, the same forms a fluid connection therebetween. v

The lifting thus imparted to the upper plunger, or the absence of the same, is utilized to control engagement of the pawl with the sprocket wheel in the manner of a triggering action to complete or leave disabled the driving connection of the shaft 57, as the case may be. Assuming chamber 72 to be sealed, initial upward movement of plunger 70 causes plunger 67 to raise, thereby to rock pawl 62 from its normal disengaged condition into engagement with the teeth of the sprocket wheel. This locks together the cars 64 and the sprocket wheel with respect to movement in the direction of desired rotation of shaft 57. As plunger 70 continues its upward travel, collar 71 thereon engages the lower end of cylinder 66, and with further elevation raises the cylinder and hence the outer ends of cars 64. The latter swing upwardly about the axis of shaft 57, and since the. ears are locked by the pawl relative to the sprocket wheel,

the shaft is rotatively advanced.

However, should air be permitted to escape from cham ber 72, initial raising of the lower plunger will not result in rocking of the pawl from its normal condition disengaged from the sprocket wheel, so that subsequent raising of the cylinder and swinging of the cars 64 will not turn the shaft. In such case, the ears are free to rotate relative to the wheel and shaft 57. Thus, the lower plunger 70 of the assembly may be continuously reciprocated with transmission of the drive force to shaft 57 under control of conditions in the cylinder air chamber. It is to be noted that a direct mechanical connection of structural elements results in the drive condition of the assembly, thereby making it possible to lift heavy loads on the platform.

The protruding lower end of plunger 70 is pivotally attached by a pin 73, around which a spacer sleeve 74 is disposed, to one arm 75 of a crank member 76. The crank is pivotally connected by a pin 77 to a support projection 78 of the housing of the valve assembly 50, with the other arm 79 of the crank extending upwardly. Arm 79 has a connection by means of a yoke and pivot pin fitting 80 to one end of a rod 81 which is, in turn, connected at its other end eccentrically to the driven element 13 of the perforator. Accordingly, operation of the perforator causes the rod 81 to reciprocate substantially horizontally, and this motion is transmitted through the crank 76 to reciprocate the plunger 70 vertically.

Returning to the valve assembly 50, the same includes a port 82 for venting the suction line of the mechanism to the atmosphere and a cover blade 83 pivoted at 84 for opening and closing such port. A spring 85 maintains the blade biased to the left in Fig. 1, while the upper portion of the blade is engaged by a collar 86 secured to the rod 81, the engagement acting in opposition to the spring action on the blade. The arrangement is such that the reciprocation of the rod and the resultant release and return of the upper portion of the blade, cooperably with the spring, causes the port 82 to be opened and closed synchronously with the perforator operation. In the strike position of the barrel valve handle 52, this port is operative in the suction line so that the suction is applied intermittently in such synchronous relation. In the stream position of the valve assembly, the port is by passed to maintain uninterrupted suction at the wheel 33, and the assembly is also desirably provided with a manually-controlled vent for cutting off suction at the valve without need for stopping the entire feeding mechanism.

On the frame of the sheet feeding mechanism, adjacent one corner of the platform 27, is a vertical support post 87 to which a rod 88 is attached at one end by a fitting 89 for swinging movement about the axis of the post and in a plane parallel to that of the platform. Rod 88 mounts a sensing assembly 90 comprising a head 91 which is slidable along the length of the rod and may be locked at any selected position therealong by means of a screw 92 passing through the head into engagement with the rod. The head supports in depending relation a vertical column 93 which is rotatable in the head and held in selected positions of angular adjustment by means of a further locking screw 94 threaded through the head into the column.

At its lower end, column 93 is provided with spaced curved ear portions 95 which support a pin 96 having a pivotal connection with one end of a generally horizontal arm 97, the construction being most clearly seen in Figs. 5 and 6. A thin feeler element 98 is attached to the free outer end of the arm, projecting downwardly from the same and having a slight reverse bend therein, as illustrated. The inner end of arm 97 supports a valve actuator 99 on an angle bracket 100, such actuator having a small projecting member 101 which may be adjusted in and out by means of a screw 102. A tension spring 103 is secured to the vertical column 93 for engagement with a shoulder portion 104 of the actuator and tends to pivot the same and arm 97 downwardly about the connection with the column. Peeler element 98 is adapted to contact the top of the stack of the sheets on the support platform and the arm will swing up and down with changes in the level of the same, lifting due to raising of the stack acting against the spring 103.

Column 94 of the feeler assembly further supports a spring plunger valve 105 of bicycle type and, accordingly, normally closed. The projection 101 of the valve actuator 99 is arranged to engage the plunger of this valve, and it will be seen that lifting of the arm 97 causes the actuator to depress the plunger and open the valve, while dropping of the arm releases the valve to its normally closed condition.

A small plastic conduit 106, which is flexible, extends from the valve to a fitting 107 attached to a vent sleeve 108 leading from the air chamber 72 within the drive cylinder 66. Since the valve is normally closed, such chamber will, therefore, be sealed and air trapped in the same serves as previously described to cause the upper plunger to move with the lower, driven plunger, the latter being operative during operation of the perforator. The lower part of fitting 107 is a standard check valve 109 arranged for entry of air therethrough to the chamber, thereby to provide quick and convenient filling of the chamber after cycles in which the chamber air is exhausted through control valve 105.

In use of the illustrated apparatus, a stack of the paper sheets to be perforated is placed on the platform 27 and the latter elevated by operation of crank handle 61 to bring the top sheet into proper position for removal by the suction wheel 33. The perforator is started, resulting in drive of the conveyor tapes 21 and of the suction wheel, and the suction producing means is energized. In initially positioning the top of the stack, contact is made with the feeler element 98 and arm 97 placed substantially in the condition shown in Fig. 5, in which the valve 105 is held open. Reciprocation of the lower plunger 70 is therefore ineffective to move the upper plunger and cause the platform-elevating means to be actuated. As the sheets are withdrawn automatically by the suction device, the top level of the stack is lowered until a condition is reached in which the follower arm 97 swings downwardly under the action of spring 103 a sufiicient extent to release the valve, this condition being shown in Fig. 6.

When this occurs, air is sealed in the cylinder chamber 72 so that reciprocation of the lower drive plunger is immediately transmitted to the upper plunger. The latter triggers the pawl for advance of the sprocket wheel 60, whereby shaft 57 is rotated and the platform is raised through the resultant drive of the support chains 32. Such drive continues until the platform has been raised enough to bring the top of the remaining stack to the desired level, at whichtime lifting of the arm 97 has caused the actuator 99 once more to open the valve 105 and thus disable the fluid connection in the drive cylinder. The operation continues in similar manner with the platform being gradually raised to maintain the uppermost sheet thereon in the proper feed position until all sheets have been fed.

It will accordingly be seen that I have provided a simple yet reliable sheet feeding mechanism which includes a driving connection with the machine to which the ma terial is fed and sensitive control means operative to render the driving connection effective or non-effective in accordance with the elevation of a supply stack of the sheets. It is to be noted that the feeler assembly provides a plurality of adjustments whereby the same may be located over any selected portion of the feed'platform. These include the angular adjustment of the mounting rod 88, the sliding adjustment of the head 91 along the length of the arm, and the further relative rotative adjustment of the vertical column 93 of the assembly. This flexibility is of considerable importance in view of the fact that sheets of widely differing size may be fed on different occasions. Thus, the platform and the con trol are adapted to provide a particular optimum region of engagement with the sheets regardless of size.

As indicated earlier, the effective drive of the shaft 57 is accomplished by direct mechanical coupling, that is, the lifting force is transmitted through crank member 76 and collar 71 of plunger 70 to cylinder 66 and from the latter to the shaft through cars 64 and the sprocket wheel. The pneumatic connection of the plunger-s here provides the triggering of the pawl; the air is not relied upon to transmit the actual force. By virtue of this construction, it is possible readily to handle and lift heavy stacks of paper, for example, weighing in the neighborhood of four hundred pounds. Where only loads of substantially less weight, on the order of one hundred fifty pounds and less, are to be handled, compressed air in the cylinder chamber may be used alone and controlled in the same manner. In this case, ears 64 would be suitably held in fixed position, lower collar 71 adjusted not to strike and lift the cylinder, and the pawl 52 adapted to advance the sprocket wheel when reciprocated by the upper plunger, the mechanism otherwise being similarly constructed and operative.

The drive means disclosed is arranged for lifting of the feed platform, since the primary application of the invention is in feeding mechanism. However, by a suitable reversal of parts, the same type of drive could be utilized gradually to lower this or a similar platform, for example where the same is adapted to accumulate sheets deposited thereon from a fixed discharge point, the platform in this case being lowered in accordance with the accumulation or increase in height of the collected sheets. It will further be apparent that the platform drive means and control thereof may be utilized with other types of stripper means than the suction wheel specifically described, for example, lifting suction arms arranged for compound movement such as commonly used in printing press feed structure.

Other modes of applying the principle of the invention may be employed, change being made as regards the details described, provided the features stated in any or the following claims, or the equivalent of such, be employed.

I therefore particularly point out and distinctly claim as my invention:

l. In sheet feeding mechanism, a support adapted to receive a stack of the sheets to be fed, drive means for raising said support as sheets are withdrawn from the top of the stack, said drive means including a cylinder, 21 first plunger mounted for limited reciprocation in said cylinder and operative to drive the latter after moving inwardly a predetermined extent, latch means actuatable to form a driving connection between the cylinder and the support, a second plunger extending into the cylinder in opposition to said first plunger and operative when moved outwardly thus to actuate said latch means, an inner chamber defined Within the cylinder between the opposed ends of the two plungers, conduit means extending from such chamber and opening to the atmosphere for the supply of air to the chamber, a normally closed valve operative to seal air in the cylinder chamber, such sealed air serving as a fluid connection between said plungers effective in initial advance of the first plunger into the cylinder to move the second plunger to actuate the latch means, whereby subsequent drive of the cylinder in continued advance is transmitted to the support for lifting of the same, the valve in open condition venting the chamber and disrupting the fluid connection so that the latch means is not actuated in such condition, such first plunger being adapted to be reciprocated continuously in operation of the mechanism, control means for regulating said valve in response to the elevation of the stack comprising a pivoted arm adapted to rest upon the top of the stack and to be raised and lowered with changes in the level thereof, said arm being operative to open the valve when thus raised to a predetermined position and to release the same to its normally closed condition in positions corresponding to lower stack levels, thereby auto matically to maintain the top of the stack at a desired level as the sheets are withdrawn, a mounting bar for said arm supported for swinging movement above the stack support and about an axis substantially normal to the support, and means adjustably securing said arm to the mounting bar at selected positions of adjustment along the latter, whereby the arm may be located above any selected portion of said support.

2. in sheet feeding mechanism, a support adapted to receive a stack of the sheets to be fed, drive means for raising said support as sheets are withdrawn from the top of the stack, said drive means including a cylinder, a first plunger mounted for limited reciprocation in said cylinder and operative to drive the latter after moving inwardly a predetermined extent, latch means actuatable to form a driving connection between the cylinder and the support, a second plunger extending into the cylinder in opposition to said first plunger and operative when moved outwardly thus to actuate said latch means, an inner chamber defined within the cylinder between the opposed ends of the two plungers, conduit means extending from such chamber and opening to the atmosphere for the supply of air to the chamber, a normally closed valve operative to seal air in the cylinder chamber, such sealed air serving as a fluid connection between said plungers effective in initial advance of the first plunger into the cylinder to move the second plunger to actuate the latch means, whereby subsequent drive of the cylinder in continued advance is transmitted to the support for lifting of the same, the valve in open condition venting the chamber and disrupting the fluid connection so that the latch means is not actuated in such condition, such first plunger being adapted to be reciprocated continuously in operation of the mechanism, control means for regulating said valve in response to the elevation of the stack comprising a pivoted arm adapted to rest upon the top of the stack and to be raised and lowered with changes in the level thereof, said arm being operative to open the valve when thus raised to a predetermined position and to release the same to its normally closed condition in positions corresponding to lower stack levels, thereby automatically to maintain the top of the stack at a desired level as the sheets are withdrawn, and means adjustably mounting said arm for positioning of the same above any selected portion of said support.

3. In sheet feeding mechanism, a support adapted to receive a stack of the sheets to be fed, drive means for raising said support as sheets are withdrawn from the top of the stack, said drive means including a cylinder, a first plunger mounted for limited reciprocation in said cylinder and operative to drive the latter after moving inwardly a predetermined extent, latch means actuatable to form a driving connection between the cylinder and the support, a second plunger extending into the cylinder in opposition to said first plunger and operative when moved outwardly thus to actuate said latch means, an inner chamber defined within the cylinder between the opposed ends of the two plungers, conduit means extending from such chamber and opening to the atmosphere for the supply of air to the chamber, a normally closed valve operative to eal air in the cylinder chamber, such sealed air serving as a fiuid connection between said plungcrs effective in initial advance of the first plunger into the cylinder to move the second plunger to actuate the latch means, whereby subsequent drive of the cylinder in continued advance is transmitted to the support for lifting of the same, the valve in open condition venting the chamber and disrupting the fluid connection so that the latch means is not actuated in such condition, such first plunger being adapted to be reciprocated continuously in operation of the mechanism, and control means for regulating said valve in response to the elevation of the stack comprising a pivoted arm adapted to rest upon the top of the stack and to be raised and lowered with changes in the level you b a 9 thereof, said arm being operative to open the valve when thus raised to a predetermined position and to release the same toits normally closed condition in positions corresponding to lower stack levels, thereby automatically to maintain the top of the stack at a desired level as the sheets are withdrawn.

4. In sheet feeding mechanism, a support adapted to receive a stack of the sheets to be fed, drive means for raising said support as sheets are withdrawn from the top of the stack, said drive means including a cylinder, a first plunger mounted for limited reciprocation in said cylinder and operative to drive the latter after moving inwardly a predetermined extent, latch means actuatable to form a driving connection between the cylinder and the support, a'second plunger extending into the cylinder in opposition to said first'plunger and operative when moved outwardly thus to actuate said latch means, an inner chamber defined within the cylinder between the opposed ends of the two plungers, conduit means extending from such chamber and opening to the atmosphere for the supply of air to the chamber, a normally closed valve operative to seal air in the cylinder chamber, such sealed air serving as a fluid connection between said plungers effective in initial advance of the first plunger into the cylinder to move the second plunger to actuate the latch means, whereby subsequent drive of the cylinder in continued advance is transmitted to the support for lifting of the same, the valve in open condition venting the chamber and disrupting the fluid connection so that the latch means is not actuated in such condition, such first plunger being adapted to be reciprocated continuously in operation of the mechanism, and control means for regulating said valve including -a feeler element adapted to be engaged by the stack to indicate a predetermined stack level, said control means being operative to open the valve in response to such indication by the feeler element, lifting of the support thereby being automatically controlled in accordance with the stack elevation to maintain the same at such predetermined level.

5. In sheet feeding mechanism, a support adapted to receive a stack of the sheets to be fed, drive means for raising said support as sheets are withdrawn from the top of the stack, said drive means including a cylinder, a first plunger mounted for limited reciprocation in said cylinder and operative to drive the latter after moving inwardly a predetermined extent, latch means actuatable to form a driving connection between the cylinder and the support, a second plunger extending into the cylinder in opposition to said first plunger and operative when moved outwardly thus to actuate said latch means, an inner chamber defined within the cylinder between the opposed ends of the two plungers, conduit means extend ing from such chamber and opening to the atmosphere for the supply of air to the chamber, a normally closed valve operative to seal air in the cylinder chamber, such sealed air serving as a fluid connection between said plungers effectivein initial advance of the first plunger into the cylinder to move the second plunger to actuate the latch means, whereby subsequent drive of the cylinder in continued advance is transmitted to the support for lifting of the same, the valve in open condition venting the chamber and disrupting the fluid connection so that the latch means is not actuated in such condition, such first plunger being adapted to be, reciprocated continuously in operation; of the mechanism, and control means operative in resppnseto a predetermined elevation of the stack to open said valve, the control means releasing the valve upon subsequent lowering of the stack level, whereby lifting of the stack is automatically controlled to maintain the same at such predetermined level.

6. In sheet feeding mechanism, a support adapted to receive a stack of the sheets to be fed, drive means for raising said support as sheets are withdrawn from such stack, said drive means including a cylinder, a first plunger mounted for limited reciprocation in said cylinder and waste operative to drive the latter after moving inwardly a predetermined extent, latch means actuatable to form a driving connection between the cylinder and the support, a second plunger extending into the cylinder in opposition to said first plunger and operative when moved outwardly thus to actuate said latch means, an inner chamberdefined Within the cylinder between the opposed ends of the plungers, valve means actuatable to positions respectively opening such chamber to the atmosphere and sealing the same, air sealed within the chamber in such latter condition of the valve means acting as a fluid con nection between the plungers effective in initial advance of the first plunger to move the other plunger to actuate the latch means, and control means operative in response to the elevation of such stack to place said valve means in sealing position when the stack level is below a predetermined point and to chamber-opening position when the stack level is at such point, the first plunger being adapted to be reciprocated continuously in operation of the mechanism, whereby lifting of the support is automatically regulated to maintain the stack at such predetermined level.

7. In sheet feeding mechanism, a support adapted to receive a stack of the sheets to be fed, drive means for raising said support as sheets are withdrawn from such stack, said drive means including a cylinder, a first plunger mounted for limited reciprocation in said cylinder and operative to drive the latter after moving inwardly a predetermined extent, latch means actuatable to form a driving connection between the cylinder and the support, a second plunger extending into the cylinder in opposition to said first plunger and operative when moved outwardly thus to actuate said latch means, an inner chamber defined within the cylinder between the plungers, conduit means connecting such chamber to a source of fluid and including valve means operative to seal fluid within the chamber, the sealed fluid acting as a connection between the plungers effective in initial advance of the first plunger to move the other to actuate said latch means, such first plunger being adapted to be connected to a power source and driven continuously thereby, and control means operative in response to the elevation of such stack to actuate said valve means to open the connection of the chamber with the fluid source when the stack is at a predetermined elevation, thereby to disable the fluid connection and hence the driving connection of the stack support, the valve means being actuated to seal the chamber when the stack is below such predetermined 1 elevation, lifting of the support thereby being automatically controlled to maintain the stack at such elevation.

8. In sheet feeding mechanism, a movable support adapted to receive a stack of the sheets to be fed, power means for gradually raising the support as the sheets are withdrawnincluding a continuously reciprocated drive member and a driven member connected with the support, coupling means selectively operative to connect and disconnect said drive and driven members, control means for actuating said coupling means in accordance with the elevation of such stack including an element arranged in opposition to said drive member and a fluid chamber between the two, conduit means connecting such chamber to a source of fluid, valve means operative to seal fluid within the chamber thereby to form a fluid connection between the drive member and the opposed control element, the latter in such condition being moved by reciprocation of the drive member to actuate said coupling means to connect the drive and driven members, the valve means being openable to disrupt such fluid connection, and sensing means for regulating operation of said valve means in response to stack elevation, the sensing means opening the valve means when the stack is at a predetermined level and effecting closure thereof at lower stack elevations.

9. In sheet feeding mechanism, a movable support adapted to receive a stack of the sheets to be fed, power means for gradually raising the support as sheets are Withdrawn including a continuously operative drive member and a driven member connected with the support, coupling means selectively operative to connect and disconnect said drive and driven members, control means for actuating the coupling means to such respective conditions in accordance with the stack elevation including a fluid connection between the coupling means and said drive member, and sensing means responsive to the elevation of the stack for disrupting such fluid connection when the stack is at a predetermined level thereby to render the coupling means inefiective, the sensing means establishing the fluid connection at lower stack levels to actuate the coupling means to connect the drive and driven members.

10. In sheet handling apparatus, support means adapted to receive a stack of sheets, power means for moving said support means vertically including a drive member adapted to be connected to a drive source and a driven member connected to the-support means, coupling means operative to connect and disconnect said drive and driven members, and said coupling means including opposed reciprocable elements and a fluid connection therebetween, control means selectively operative to limit displacement of the fluid forming such connection in a drive condition of said power means and to provide for displacement of the fluid in a non-driving condition, and sensing means responsive to the elevation of such stack operative to place said control means in such nondriving condition when the stack is at a predetermined level and in drive condition when the stack is displaced from such level.

ll. in sheet handling apparatus, a support adapted to receive a stack of the sheets,fdrive means operative to move said support vertically including two opposed reciprocable members and a fluid chamber therebetween, one of said members being adapted to be reciprocated by power means and the other to transmit such drive to the support, conduit means connecting such chamber to a source of fluid, valve means operative to seal fluid within the chamber, the sealed fluid acting as a connection effective to transmit reciprocation of the power driven member to the other member, and control means operative in response to the elevation of such stack to actuate said valve means to open the connection of the chamber with the fluid source when the stack is displaced to the rear of a predetermined level in the direction of movement of the support.

12. in sheet handling apparatus, a support adapted to receive a stack of the sheets to be fed, drive means for moving said support vertically including a cylinder having a pair of opposed plungers mounted for reciprocation in the same, one of said plungers being adapted to be driven by power means and the other to transmit such drive to the support, an inner chamber defined within the cylinder between the opposed ends of the plungers, conduit means connecting such chamber to a source of fluid and including valve means operative to seal fluid within the chamber, the sealed fluid acting as a connection effective to transmit reciprocation of the power driven plunger to the other plunger, and control means operative in response to the elevation of such stack to open the connection of the chamber with the fluid source when the elevation of the stack is to the rear of a predetermined level in the direction of movement of the stack support.

13. In sheet handling apparatus, a support adapted, to receive a stack of the sheets, drive means for moving said support vertically including a cylinder having a pair of opposed plungers mounted for reciprocation in, the same, one of said plungers being adapted to be reciprocated continuously in operation of the mechanism, and the other to transmit such drive to the support, an inner chamber defined within the cylinder between the opposed ends of the plungers, valve means actuatable to positions respectively opening such chamber to the atmosphere and sealing the same, air sealed with the. chamber in such latter condition of the valve means acting as a fluid connection between the plungers eflec: tive to transmit reciprocation of the continuouslyoperative plunger to the other plunger, and control means operative in response to the elevation of such stack to; actuate said valve means to chamber-opening position when the stack is at a predetermined level and to sealing position when the stack is to the rear of such level in the direction of support movement. v

14. In combination, a shaft, a sprocket wheel thereto, a link rotatably mounted on said shaft,.a pawl pivotally secured to said link and adapted to engage the sprocket wheel thus to lock the link rotatively to the wheel in the desired direction of shaft rotation, a plunger operative to actuate the pawl into such lock.- ing engagement with the wheel, a cylinder securedto said link and reciprocably receiving said plunger, a further plunger reciprocably mounted in said cylinder in opposition to the first-mentioned plunger andoperative to drive the cylinder in a latter position of its forward stroke, a chamber between said plungcrs containing air. which serves to transmit reciprocation of the further plunger to the plunger actuating the pawl in the initial advance of the former, whereby the cylinder drive. of the link drives said shaft, and condition responsive means I for venting said chamber thereby to disrupt such transmission upon the occurrence of a prdctennihedlcondi-T tion, the pawl in such condition being disengagedlfro m, the wheel so that the shaft is not driven by movement or the cylinder and link. I

15. In sheet handling apparatus, a vertically movable platform, drive means therefor including a shaft, "is sprocket wheel on said shaft, a link carried byand. extending from the shaft, a pawl pivotally supported by said link and adapted to engage the sprocket wheel in drive relation therewith, a plunger operative thus to;

actuate the pawl, a cylinder secured to the link and:

reciprocably receiving said plunger, a further. plunger reciprocably mounted in said cylinder in opposition to. the first-mentioned plunger, a chamber withinthe cylinder between the two plungers containing air which serves to transmit reciprocation of the further plunger tofthc plunger actuating the pawl, and sensing means rcspon sive to the elevation of said platform, said sensing means being operative to vent said chamber therebyto disrupt such transmission when the platform is to the rear of a predetermined elevation in its vertical movement. i

References Cited in the file of this patent UNITED STATES PATENTS Williams Oct. 6, 1953- 

